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Once a very familiar sight across the railways of southern England, the 4CIG electric multiple unit is a classic example of the heritage ‘slam-door’ passenger trains which once formed the backbone of southern passenger services.

Extensive 3rd-rail electrification of the Southern Region led to the widespread adoption of these practical EMUs, and the 4CIG (British Rail Class 421) was initially introduced on the London-Brighton Line before being pressed into service on the Portsmouth Direct Line between London Waterloo and Portsmouth Harbour.

The 4CIG units received a facelift in the late 1980s, and were eventually withdrawn from mainline passenger service in the early 2000s.